SINGAPORE has challenged Malaysia's trade practices for the second time in less than two weeks. On Friday, Singapore levied a S$111 (about HK$590) per tonne anti-dumping duty on steel bars imported from Malaysia's Amsteel Corporation. Amsteel charges $111 more for its product in Malaysia than it does in Singapore, says the Singapore Trade Development Board. The board said the Malaysian company's practice was hurting Singapore's domestic industry and it had evidence that Malaysia was dumping the product. Singapore-listed NatSteel Ltd made a formal complaint to the TDB in December about Amsteel's alleged dumping practices. NatSteel has also made a complaint about five Turkish steel mills, but the TDB has yet to take any formal action on those complaints. Singapore said that it was acting in accordance with the rules of the new World Trade Organisation (WTO) in imposing the anti-dumping duty on Amsteel. The TDB said that under new WTO rules, the Singapore Government now had four months to complete its investigation and make a final decision about the duty. Earlier this month, the government referred another trade dispute with Malaysia to the WTO. Singapore argued that Malaysia's permit requirements for the import of certain petrochemicals acted as a non-tariff barrier to Singapore exports, and that such barriers were against both the letter and the spirit of the General Agreement on Tariffs and Trade and the WTO. Malaysia's Minister for Trade and Industry, Rafidah Aziz, said import permits had not restricted Singapore's exports. He said they were necessary to allow Malaysia to build up its petrochemical industry.